Sail Trim And Balance Fundamental

Fundamental Sail Trim and Balance with Kristen “kb” Berry

Sail Trim and Balance • The Big Question • One Language • Two Modes • Three Sources of Power • Controls • Balance • Putting it all together

What makes a boat go?

Let’s Develop a Common Sail Language

One Language • Most sails have three edges • Most sails have three corners

One Language

One Language Luff

One Language Leech Luff

One Language Leech Luff Foot

One Language Head Leech Luff Foot

One Language Head Leech Luff Foot Tack

One Language Head Leech Luff Clew Foot Tack

One Language LUFF Chord Draft Camber Leech

What are the Two Modes of Sailing? • Fast and Slow? • Cruising and Racing? • Upwind and Downwind?

TWO MODES PUSH PULL

Push Mode

Push Mode • Sail acts as a WIND block to the wind. • More wind = more power H H • More area = LL more power

Pull Mode

Pull Mode • Attached air WIND ﬂows over both sides from leading to trailing edge • Outside air ﬂows faster because of L H camber H L • Creates heel & forward force

Pull Mode - Keel Lift Keel Lift • Keel lift works the same way, below the water. L • Water ﬂows over the curved surface of the keel. Leeway • Because of leeway, high H pressure builds on the LEEWARD side and keel lift occurs.

Pull Mode - The Watermelon Seed • When Sail Lift and Keel Combined Lift balance, the boat Force moves forward Keel Lift • Keels takes us upwind and sails take us downwind • We must have ﬂow and Sail Lift balance

Pull mode is really FLOW mode.

So what mode are you sailing in?

CLOSE HAULED

Beam Reaching

Broad Reaching

WIND Close Hauled No Go ZONE Beam Reach Broad Reach Run

What are the three sources sail power?

Angle of Attack The angle of a sail’s CHORD to the apparent wind.

WIND WIND WIND 0 45 60 Lufﬁng Proper AoA Stalled

So what do telltales show us about AoA?

Attached Airﬂow Luff

Attached Airﬂow Leech

When in doubt... Let it out, until it luffs. Often doubt... Rarely in error.

Draft The AMOUNT of camber in a sail and the LOCATION of the deepest point of camber.

Flat Deep Shape Shape Horizontal Profile: A deeper sail is more powerful but will also generate more drag. A flat sail has less drag, but generates less power in lighter winds. Deeper sails for light air and flatter sails for heavier air.

Flat Mainsail Shape

Deep Mainsail Shape

Deep sails for light air. Flat sails for heavy air.

Twist The difference in Angle of Attack from head to foot of a sail. The amount of leeward falloff of a sail’s leech.

UPWIND TWIST Note the top batten relative to the boom. Both are showing the CHORD of the mainsail. The top batten is pointing to leeward while the boom is pointing behind the boat.

DOWNWIND TWIST Twisting OPEN the leech allows the wind to ﬂow freely from leading edge to trailing edge. More twist equals more ﬂow.

TWIST Wind Speed

Sail Controls • Primary Mainsail Controls • Primary Jib/ Genoa Controls

Main Controls Angle of Attack Draft Twist Angle of Chord to Wind Amount and Location Difference in AoA Halyard ✔ Sheet ✔ ✔ Traveler ✔ Vang ✔ ✔ Outhaul ✔ Backstay ✔ ✔ Cunningham ✔

Jib/Genoa Control Angle of Attack Draft Twist Angle of Chord to Wind Amount and Location Difference in AoA Halyard ✔ Sheet ✔ ✔ ✔ Lead Car Blocks ✔ ✔ ✔ Backstay ✔

BALANCE • How does sail trim affect affect balance? • How does heel affect balance?

Mainsail Center of Headsail Effort Center of Effort ☢ ✇☢ Combined Center of Effort Center of ✇ Lateral Resistence

Boat Sails Boat Turns Straight To Port View from astern Boat is heeled Boat is level to starboard

☢ ☢ View from astern ✇ ✇ Boat is level Boat is heeled And TURNING and steering straight

What do we want? When do we want it? and how do we get it?

Light Air Days • GIVE ME POWER! • MORE FLOW! • MORE DRAFT! • MORE TWIST!

Light Air Days No Stall! Eased sheets, boom off AoA centerline. All telltales streaming aft. Not steering close hauled. Ease halyard, outhaul, backstay, Draft cunningham. Move jib lead forward. Open twist to promote ﬂow at top Twist of sail. Jib and main should “match” Leeward heel to promote sail camber. Forward weight to reduce Balance drag. Trim crew weight to helm “feel.” Slight tug.

Moderate Air Days • No compromises • Max point and speed • Minimum Twist • Design Draft • Design Heel - Flatter is faster

Moderate Air Days Max trim, slight stall for point. Boom on centerline. Inside jib AoA telltale lifting, top leech telltale slight stall. Draft Moderate depth, starting to ﬂatten Twist No twist for maximum power. Designed heel. Less than 10 Balance degrees. Trim crew weight to helm “feel.” Neutral tug.

Heavy Air • WHOA!!!!!! • Depower sails • Open AoA for waves • Keep the boat balanced

Heavy Air Days Traveler down for open AoA. Jib/ AoA Genoa eased or even moved outboard Flat, Flat, Flat. Tight halyards and Draft OBC’s Twist Lots of twist to help depower. Reduce heel by moving crew weight Balance to windward. Balance CEs to keep helm pressure to light tug.

Thank you! • Let’s go sailing! • Submit your question cards. • Stay in touch - my pledge to you. • Resources.

SAIL FAST, SAIL SAFE AND STAY IN TOUCH KRISTEN BERRY KRISTEN@JWORLDANNAPOLIS.COM www.galeforcesailing.com PHONE - 202-549-1032

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Sail Trim And Balance Fundamental

by Kristen Berry on Mar 13, 2010

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